We propose to organize a Workshop on Electron Crystallography of Macromolecules at Granlibakken Conference Center in Lake Tahoe, California, between December 9-12, 1998. The motivation of this workshop is to based on the recent advances in this field of structural biology capable of resolving biological structure details at 3-10 Angstrom units resolution range. The Workshop will focus on recent dramatic advances in four branches of electron crystallography, emphasizing both methodology development and the elucidation of intermolecular interactions in large macromolecular assemblies. Particular attention will be paid to proteins - both integral membrane components and non-membrane proteins - in crystalline monolayers; probing intermolecular interactions by fitting high resolution subunit structures into lower resolution maps of intact complexes; analysis of filaments and free-standing particles at subnanometer resolution; and a novel method of phasing native X-ray data based on exploiting EM- derived molecular envelopes and non-crystallographic symmetry. The goal of the Workshop is to summarize these and related lines of investigation, assess the prospects for further methodological improvement (higher resolution, accelerated analysis), and stimulate their application to a more extensive set of biological problems. Another important purpose of this Workshop is to disseminate this emerging structural biology tool to the cell and molecular biology community. We will make an attempt to attract participants from non structural biology discipline attending this meeting via a variety of means of advertising the Workshop and scheduling it right before the 1998 Cell Biology Annual Conference to be held in San Francisco. For a broader dissemination, we plan to publish a special issue of the envisaged topics in the Journal of Structural Biology contributed from the invited participants.